Researchers Spot Giant Sharks off Corcovado

March 20, 2009

Researchers with the ocean conservation organization PRETOMA were pulling in their fishing line when they realized they had caught a little more than they had bargained for: what is believed to be a bull shark measuring approximately four meters (13 feet) in length.

“It was very close to the surface. We were pulling it in when the line broke,” said Allan Bolaños, a researcher who was aboard a boat about two kilometers off the coast of the southern PacificOsaPeninsula when he and others spotted the massive shark.

Bolaños and a group of researchers were in the region to capture bull sharks in order to outfit them with tracking devices in order to study their movements. The fishing lines the scientists were using, however, were no match for the largest of these sharks, PRETOMA said in a statement released last week.

“Many of the hooks and steel leaders were mangled, destroyed, or simply bitten off by the large animals, only one of which came close enough to our fishing vessel for us to take a glimpse of its amazing size, before it too broke free,” said Randall Arauz, the expedition’s scientific director.

Bull sharks, particularly juveniles, are known to swim up freshwater rivers in search of food and protection. Bull sharks have been seen far up the San Juan River, which forms Costa Rica’s northern border with Nicaragua, and are believed to inhabit Lake Nicaragua, the river’s source.

On average, bull sharks range between 2.1 and 3.4 meters, and are classified as “near threatened” by the International Union for the Conservation of Nature (IUCN).

As part of the Bull Shark Tagging Project, the researchers captured and tagged four juvenile bull sharks measuring approximately one meter in the brackish waters where the SirenaRiver meets the ocean, at the edge of CorcovadoNational Park. Bolaños and others are studying the movement patterns of the sharks in the hopes of expanding the national park’s boundaries to cover more of the sea.

Currently, Bolaños said, the park’s protected status extends 500 meters into the ocean, an area where fishing is prohibited. The four-meter bull shark was spotted two kilometers from shore.

The research project is funded by the Whitley Fund for Nature (WFN), the BBC Wildlife Fund and corporate sponsors through PRETOMA’s Corporate Membership program.

–Leland Baxter-Neal

 

You may be interested

Adaptive surfing, part II: The story of Dean Bushby
sports
139 views
sports
139 views

Adaptive surfing, part II: The story of Dean Bushby

Ellen Zoe Golden - May 22, 2018

A three-part look at adaptive surfing in Costa Rica. Read Part I here to learn how a Central Pacific coach is…

Costa Rica launches Pride Connection network
Human rights
171 views
Human rights
171 views

Costa Rica launches Pride Connection network

Elizabeth Lang - May 22, 2018

As Costa Rica continues to grapple with the disagreements about marriage equality and gender identity that dominated the second round…

Costa Rica at a glance: top news from the past week
The Alvarado Administration
199 views
The Alvarado Administration
199 views

Costa Rica at a glance: top news from the past week

The Tico Times - May 21, 2018

Newly inaugurated Costa Rican President Carlos Alvarado is closing in on two weeks on the job. Here are some of…